Heat Weld Tubing Connectors

ABSTRACT

The present invention provides thermoplastic tubes, thermoplastic melting plates, thermoplastic tube connecting apparatus, and methods for using the same.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of patent application Ser. No.11/772337, filed Jul. 2, 2007 which claims the benefit of U.S.Provisional Application No. 60/819,446, filed Jul. 7, 2006.

FIELD OF THE INVENTION

The invention relates to thermoplastic tubes, thermoplastic meltingplates, thermoplastic tube connecting apparatus, and methods for usingthe same.

BACKGROUND OF THE INVENTION

Containers with tubing are used for various medical procedures such askidney dialysis, intravenous delivery of therapeutic fluids, delivery ofnutritional fluids; delivery of blood, blood components, and bloodsubstitutes. Particularly in blood banking, connections are frequentlyused between the containers and associated tubing. Such applications mayrequire connecting two or more different containers to one another, eachof which typically contains a different sterile material. For example,in the blood-banking environment, a bag containing sterile solution maybe connected to an apheresis kit containing tubing. Regardless of anyparticular application, in most cases connections between two tubes areformed.

Connecting the tubing typically involves using a sterile tube weldingmachine to weld the thermoplastic tubing in a sterile manner. There aremany sterile tube welding machines known to one skilled in the art. Onetype of tube welding machine sterilizes a cutting blade or wafer thenmoves the blade through the two ends of the tubing to be joined. Onceboth ends of the tubing have been cut, the machine aligns the ends ofthe tubes while maintaining a high temperature. After the thermoplastictubes cool, a sterile weld is formed. Other tube connection systems haveapplied heat to the ends of the tubing sections without requiring directcontact of heating elements with the tubing sections. See, for example,U.S. patent application Ser. No. 10/061,835, filed Jan. 31, 2002; Ser.No. 10/251,681, filed Sep. 20, 2002; Ser. No. 10/251,682, filed Sep. 20,2002; and Ser. No. 10/251,683, filed Sep. 20, 2002, all of which areincorporated herein by reference in their entirety. Regardless of thetype of tube welding device utilized, connecting the ends of the tubesections requires a precise alignment of the tube ends due to therelatively small wall thickness of the tube.

Sterile tube welding devices may have a relatively low level ofreliability due to the inconsistency in aligning the tube ends followingthe melting and cutting processes. The inconsistency of operation canresult in imperfect seals, leading to leaks, and microorganisminfiltration, which may lead to infection. In addition, the interiorpassages of the tubing sections are initially sterile, but in someinstances cutting the tubing sections so that connections of adjacentsections can be made exposes the interior passages of the tubingsections to the surrounding environment, allowing them to potentiallybecome contaminated with airborne contaminants, e.g., bacteria. In orderto avoid exposure of the interior passage (i.e., lumen) of each tubingsection, some tube welding devices clamp the end portion of the tubingsection shut before an end portion of the tubing section is cut.

In some systems a hot blade or other heated surface is brought intocontact with the tubing sections to bring them up to meltingtemperature. The ends of the two tubing sections are then broughttogether so that the melted ends fuse, connecting the tubing sectionstogether. The clamps collapsing the respective end portions of thetubing sections are released and the tubing sections open, defining acontinuous, sealed interior passage through the connected tubingsections. Unfortunately, the connection must often be manually openedand/or examined to ensure proper seal, thereby increasing the time andlabor.

For tube welding devices that utilize a hot plate for producing moltenthermoplastic and welding molten tubes, another disadvantage is that intime the hot plate becomes fouled with the plastic material, e.g., somethermoplastic resin may adhere to the hot plate, requiring occasionalcleaning of the hot plate to maintain sterile operating conditions orusing disposable cutting blades, thereby increasing the overall time andcost.

Accordingly, there is a need for various improvements in thermoplastictube weld connecting devices.

SUMMARY OF THE INVENTION

One aspect of the present invention provides a thermoplastic tubecomprising an inner diameter, an outer diameter, and a sealed end. Thecross section defined by the outer diameter of the thermoplastic tube ofthe present invention is substantially greater proximal to the sealedend relative to the cross section distal to the sealed end. In addition,the wall thickness defined by difference between the outer and the innerdiameter is substantially greater proximal to the sealed end relative tothe wall thickness distal to the sealed end.

In some embodiments, the wall thickness proximal to the sealed end is atleast about 50% greater than the wall thickness distal to the sealedend. Within these embodiments, the wall thickness proximal to the sealedend is at least 250%, and in another embodiments it is at least 350%,greater than the wall thickness distal to the sealed end.

In other embodiments, the wall thickness of the thermoplastic tubeproximal to the sealed end is at least about 0.8 mm. Within theseembodiments, typical wall thickness proximal to the sealed end is fromabout 1.1 mm to about 1.4 mm. In further embodiments the wall thicknessproximal to the sealed end is at least about 2 mm.

In some embodiments, the sealed end comprises a thermoplastic cap havinginserted therein a thermoplastic tube. In these embodiments, thethermoplastic cap and the thermoplastic tube are hermetically sealed toform the sealed end. Within these embodiments, in some instances, thethermoplastic cap comprises a flange. The melting temperature of thethermoplastic cap and the thermoplastic tube can be the same ordifferent. In some instances, the melting temperature of thethermoplastic cap is different than the thermoplastic tube. In oneembodiment, the melting temperature of the thermoplastic cap is lowerthan the melting temperature of the thermoplastic tube. Typically, themelting temperature of the thermoplastic cap is about 20° to 100° C.lower than the melting temperature of the thermoplastic tube.

In some embodiments the thermoplastic tube inserted in the thermoplasticcap is co-extruded from two thermoplastic materials having differentmelt temperatures. Typically, the melting temperature of the tubinginner layer is about 20° to 100° C. higher than the melting temperatureof the outer layer and the cap. Exemplary instances include a tubingcomprising polyolefin inner layer with PVC outer layer (available fromKelcourt Plastics Inc.), and a tubing dual layer PVC comprising a highdurometer inner layer PVC and a lower durometer outer layer. In some ofthese particular embodiments, the thickness of the inner layer can bevaried to yield desired self-opening performance.

As mentioned above, in one embodiment the thermoplastic tube furthercomprises a flange proximal to the sealed end. The flange can servevarious purposes including, but not limited to, as a stopping referencepoint when joining the tube ends together, and aiding in opening thelumen (i.e., interior of the tube) after joining the tube ends together,etc.

Still in other embodiments, the thermoplastic tube further comprises asealed vessel. Generally the sealed vessel is connected distal to thesealed end of the thermoplastic tube. However, it should be appreciatedthat the sealed vessel can be attached along any portion of thethermoplastic tube depending on a particular application and/or desiredconfiguration. Within these embodiments, in some instances, the sealedvessel is a plastic bag.

Another aspect of the invention provides a thermoplastic cap that isadapted to provide a sealed thermoplastic tube end when a thermoplastictube is connected to and hermetically sealed with the thermoplastic cap.The thermoplastic cap comprises:

-   -   an orifice for receiving a thermoplastic tube, where the        diameter of the orifice is adapted to be hermetically sealed        with the thermoplastic tube when the thermoplastic tube is        connected to the thermoplastic cap;    -   a channel in fluid communication with the orifice and having a        diameter that is different than the diameter of the orifice;    -   a wall positioned between the orifice and the channel such that        it is adapted for providing a stopping point during a process        for joining or connecting the thermoplastic tube with the        thermoplastic cap; and    -   a sealed end at the end of the channel.

In some embodiments, the thermoplastic cap further comprises a flange onthe outer surface. In this manner, one can use the flange to aid inopening the lumen after joining or connecting the thermoplastic tubeends.

Another aspect of the invention provides a method for connecting firstand second thermoplastic tubes together transversely of the axis of eachtube. The method generally comprises:

-   -   forming molten thermoplastic ends from first and second        thermoplastic tubes, where each of the first and the second        thermoplastic tubes comprises:        -   an inner diameter defining a lumen,        -   an outer diameter; and        -   a sealed end,    -   where the cross section defined by the outer diameter is greater        proximal to the sealed end relative to the cross section distal        to the sealed end, and wherein the wall thickness defined by the        difference between the outer and the inner diameter is greater        proximal to the sealed end relative to the wall thickness distal        to the sealed end; and    -   moving the respective molten ends of the thermoplastic tubes        together to form a joint between the first and the second        thermoplastic tubes.

In some embodiments, each of the first and the second thermoplastic tubecomprises a plurality of thermoplastic tubes. In this manner, aplurality of thermoplastic tubes are connected simultaneously.

Still in some other embodiments, the step of forming moltenthermoplastic ends comprises contacting each of the sealed ends to aheat transferring material that is heated to a temperature that is atleast equal to the melt temperature of the thermoplastic ends. It shouldbe appreciated that other means of heating the thermoplastic tube thatdo not require a direct physical contact can also be used, such asheating with a laser beam, heating with air convection or flow, usingradiated heat, using microwave heating, radio frequency heating, etc.

Still in other embodiments, methods of the invention further comprisesubstantially flattening the sealed end of each thermoplastic tube suchthat the lumen at a position to be connected, e.g., proximal to thesealed end, is substantially closed prior to the step of forming moltenthermoplastic ends. When the sealed end of the thermoplastic tube isflattened and the internal volume approaches zero, the tip of the sealedend protrudes axially to extend the overall length of the tube towardsthe heating element. This protrusion is desirable, in that, if theopposite were to occur the likelihood of sterile connection is believedto be significantly lower. For example, if the closed tip were toinvert, the melt flow extrusion would not occur entirely in a radialdirection, as desired, but some component of the melt flow may movetowards center of tubing, preventing sterility and self-opening. Thiscollapsing feature also provides a minimum trapped volume between thetubing clamp and the heated end of the tube. If trapped volume existsduring melt, the air or liquid may expand and/or vaporize therebyincreasing the possibility of creating an external leak path notcontained by the melt.

In some instances within these embodiments, the sealed end of the tubeis designed to provide the above described protrusion during collapse.Any suitable tubing design that can accomplish this desiredconfiguration can be employed in the invention. One exemplary methodincludes a tubing configuration where the most proximal end of thesealed tubing having the smallest wall thickness. Such a configurationcauses the sealed end to initiate movement first as the tubing iscollapsed. Furthermore, a small central protruding feature within thesmallest wall thickness initiates collapse in the correct direction andprevents or reduces the likelihood of inversion collapse.

Within these embodiments, in some instances, the method furthercomprises opening the lumen after forming the joint between the firstand the second thermoplastic tubes. Such opening of the lumen may occurwithout the aid of any external force, or it can be aided with anexternal force. Typically, opening of the lumen is carried outimmediately after forming the joint between the first and the secondthermoplastic tubes. However, it should be appreciated, that the lumencan be opened anytime after the joint between the first and the secondthermoplastic tubes has been formed.

Yet in other embodiments, the step of contacting the thermoplastic tubesto the heat transferring material comprises providing a means for havingmolten thermoplastic flow substantially away from the lumen of eachtube. This molten thermoplastic flow away from the lumen maintainsaseptic conditions of the thermoplastic tube ends that are beingconnected.

Another aspect of the present invention provides a method for forming asterile connection between a first thermoplastic tube and a secondthermoplastic tube each comprising a sealed end. This method comprises:

-   -   forming a molten thermoplastic end from each sealed end of the        first and the second thermoplastic tubes such that each of the        surface area of the molten thermoplastic to be joined is a        substantially greater than the cross-sectional area of the        sealed end; and    -   moving the respective molten ends of the thermoplastic tubes        together to form a joint between the first and the second        thermoplastic tubes such that the joint comprises a flange        formed from bonding of the molten thermoplastic from the first        and the second thermoplastic tubes.

Without being bound by any theory, it is believed that having thesurface area of the molten thermoplastic greater than that of thecross-sectional area of the sealed end of the thermoplastic tube allowsfacile and/or stronger adhesion between the first and the secondthermoplastic tubes. The flange formed by the molten plastic can furtherserve as visual indication of a successful weld, thus providing meansfor quality control.

In some embodiments, the surface area of the molten thermoplastic flangeis at least equal to the cross-sectional area of the sealed end. Thesurface area of the molten thermoplastic flange refers to thecross-sectional area, which is transversal to the tube axis, of theflange formed by the molten thermoplastic. Typically, however, thesurface area of the molten thermoplastic flange extends beyond the outerdiameter of the sealed end. In this manner, when the tubes areconnected, the molten thermoplastic flange extends above the outerdiameter of the joined thermoplastic tubes. Within these embodiments,the surface area of the molten thermoplastic is in one embodiment atleast 250%, and in another embodiment at least 500%, greater than thecross-sectional area of the sealed end.

Still in some other embodiments, methods of the invention furthercomprise substantially flattening the sealed end of each thermoplastictube such that the lumen at a position to be connected is substantiallyclosed prior to the step of forming molten thermoplastic ends.

Yet in other embodiments, the step of forming molten thermoplastic endscomprises contacting each sealed end of the first and the secondthermoplastic tubes to a hot plate thereby melting the sealed end toform the molten thermoplastic end. Within these embodiments, in someinstances the step of contacting the thermoplastic tubes to the heattransferring material further comprises providing means for havingmolten thermoplastic flow substantially away from the lumen of eachtube. In many instances, excess molten thermoplastic is formed byfurther advancing the thermoplastic tubing ends into the hot plate afterinitial contact has been made between the thermoplastic tube end and thehot plate. This produces excess molten thermoplastic flow away from thelumen and provides a sterile molten thermoplastic zone near the lumenfor forming a sterile connection.

Yet another aspect of the invention provides a method for connectingfirst and second thermoplastic tubes together transversely of the axisof each tube, e.g., end-to-end connection, without a need for anexternal force to open an interconnecting lumen. Such method comprises:

-   -   forming molten thermoplastic ends from first and second        thermoplastic tubes, where each of the first and the second        thermoplastic tubes comprises:    -   an inner diameter defining a lumen,        -   an outer diameter; and        -   a sealed end, and        -   moving the respective molten ends of the thermoplastic tubes            together to form a joint between the first and the second            thermoplastic tubes; and        -   allowing the interconnecting lumen to open.

In some embodiments within this aspect of the invention, thethermoplastic wall thickness proximal to the sealed end has a sufficientelasticity modulus to cause an interconnecting lumen to open after thetubes have been connected. Typically, the wall thickness of thethermoplastic tube is such that the wall's elasticity modulus and/or thewall's elasticity modulus in combination with the elasticity modulus ofthe flange integral to the thermoplastic cap cause the interconnectinglumen to open without the need for any external force.

In some embodiments, the wall thickness proximal to the sealed end is atleast about 1.2 mm. In other embodiments, the wall thickness is at leastabout 1.8 mm. Still in other embodiments, the wall thickness at leastabout 3.6 mm.

Still another aspect of the invention provides a thin thermoplasticmelting plate adapted to be used with a heat weld thermoplastic tubeconnecting apparatus. The thermoplastic melting plate comprises a heattransferring material that is adapted for melting a thermoplastic tubeto produce molten thermoplastic. The thermoplastic melting plate furthercomprises:

-   -   a front surface;    -   a back surface;    -   an insulating material (i.e., heat insulating material)        substantially covering the front and back surfaces;    -   an exposed heat transferring material portion within the front        and the back surfaces of the insulating material such that the        exposed portion is adapted for melting the thermoplastic tube to        produce molten thermoplastic; and    -   an interface portion for operatively connecting the        thermoplastic melting plate to the heat weld thermoplastic tube        connecting apparatus.

In some embodiments, the insulating material comprises aluminumsilicate, a heat insulating ceramic, or a combination thereof.

In other embodiments, the exposed heat transferring material portion isadapted for contacting the thermoplastic tube to produce moltenthermoplastic.

Yet in other embodiments, the exposed heat transferring material portionis adapted to produce molten thermoplastic from the thermoplastic tubewithout directly contacting the thermoplastic tube.

Still in other embodiments, the interface portion is adapted to beoperatively connected to a heating element of the heat weldthermoplastic tube connecting apparatus. In this manner, the heatingelement of the heat weld thermoplastic tube connecting apparatus heatsthe thermoplastic melting plate, thereby allowing the thermoplasticmelting plate to heat and melt thermoplastics during its operation.

Yet another aspect of the invention provides a thermoplastic tubeconnecting apparatus comprising a removably attached thin heattransferring material that is adapted for melting a thermoplastic tubeto generate a molten thermoplastic tube end. The thin heat transferringmaterial comprises:

-   -   a front surface;    -   a back surface;    -   an insulating material substantially covering the front and back        surfaces;    -   an exposed heat transferring material portion within the front        and the back surfaces that is adapted for melting the        thermoplastic tube to produce a molten thermoplastic tube end;        and    -   an interface portion for operatively connecting the        thermoplastic melting plate to a heat weld thermoplastic tube        connecting apparatus.

In some embodiments within this aspect of the invention, the exposedheat transferring material portion is adapted for contacting thethermoplastic tube to produce molten thermoplastic. In otherembodiments, the exposed heat transferring material portion is adaptedto produce molten thermoplastic from the thermoplastic tube without anydirect contact with the thermoplastic tube.

Still in other embodiments, the interface portion is adapted to beoperatively connected to a heating element of the heat weldthermoplastic tube connecting apparatus.

Still another aspect of the invention provides a thermoplastic tubeconnecting apparatus comprising:

-   -   a thermoplastic melting plate that is adapted for melting a        thermoplastic tube thereby producing a molten thermoplastic tube        end; and    -   a thin film that is adapted for being placed between the        thermoplastic tube and the thermoplastic melting plate such that        the thermoplastic tube does not directly contact the        thermoplastic melting plate during its operation.

In some embodiments, the thermoplastic melting plate is a thin heattransferring material.

The thin film can comprise polytetrafluoroethylene (Teflon®), thinmalleable metallic sheets (such as aluminum foil and copper foil),polyester, Q Foil (available from EGC Enterprises Inc., Chardon, Ohio),or a combination thereof.

Still in other embodiments, the thermoplastic tube connecting apparatusfurther comprises a means for allowing a different portion of the thinfilm surface to come in contact with thermoplastic tubes during eachthermoplastic tube connecting operation.

In some embodiments, the thermoplastic tube connecting apparatus furthercomprises a thin film traversing element for traversing, e.g., moving,the thin film relative to the thermoplastic melting plate therebyallowing a clean or different portion of the thin film to be contactedwith the thermoplastic tubes during each thermoplastic tube connectionoperation.

Still another aspect of the present invention provides a method forconnecting first and second thermoplastic tubes together transversely ofthe axis of each tube. This method of the invention comprises:

-   -   contacting the first and the second thermoplastic tubes to a        thin film that is operatively connected to a thermoplastic        melting plate to generate molten first and second thermoplastic        tube ends; and    -   moving the respective molten ends of the thermoplastic tubes        together to form a joint between the first and the second        thermoplastic tubes.

In some embodiments, each of the first and the second thermoplastictubes comprises a plurality of thermoplastic tubes, thereby allowingmultiple thermoplastic tubes to be sterilely connected simultaneously.

In some embodiments within this aspect of the invention, the methodfurther comprises moving or traversing the thin film relative to thethermoplastic melting plate during and/or after each operation therebyallowing clean or different area of the thin film to be contacted withthe thermoplastic tubes during each thermoplastic tube connectionoperation.

In other embodiments, the methods and apparatus provide for theconnection of a plurality of first and second thermoplastic tubes usinga plurality of think melting plates for generating the moltenthermoplastic ends. In still other embodiments, a single thermoplasticmelting plate is used for connecting a plurality of first and secondthermoplastic tubes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are a schematic, fragmentary longitudinal section viewof a thermoplastic tube having a sealed end;

FIGS. 2A-2D are a schematic, longitudinal section view of variousthermoplastic cap configurations;

FIGS. 3A-3G are schematic illustrations of various steps in connecting afirst and a second thermoplastic tubes together transversely of the axisof each tube;

FIG. 3H is a transversal cross-sectional illustration of one of thethermoplastic tubes shown in FIG. 3D;

FIG. 4A is a schematic cross-sectional view of a thermoplastic meltingplate and the thermoplastic tube;

FIGS. 4B and 4C are a side view of various thermoplastic melting plateconfigurations;

FIGS. 5A and 5B are cross-sectional view of a thermoplastic tubeconnecting apparatus comprising a thin film that is designed to preventa direct contact between a hot plate and a thermoplastic tube;

FIG. 5C is a perspective view of a thermoplastic tube connectingapparatus of FIGS. 5A and 5B comprising a plurality of thermoplastictube holders that can be used to simultaneously connect a plurality ofthermoplastic tubes;

FIG. 6 is a schematic illustration of simultaneously connecting aplurality of thermoplastic tubes such as in platelet separation frombuffy coats;

FIG. 7 is another schematic illustration of simultaneously connecting aplurality of thermoplastic tubes; and

FIG. 8 is a close-up cross-sectional view of a thermoplastic tubeholder.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides various thermoplastic tubes,thermoplastic melting plates, thermoplastic tube connecting apparatus,and methods for using the same. Devices and methods of the presentinvention are particularly useful, although not necessary, in asepticthermoplastic tube connection.

Some of the problems associated with conventional thermoplastic tubeconnecting methods are that the thermoplastic tube connection jointssometimes leak thus requiring carefully inspection and sometimesrequiring the resulting products associated with the connection bediscarded. Some of the methods and devices of the invention eliminate orgreatly reduce the failure rate (i.e., leakage) of thermoplastic tubeconnection. Accordingly, methods and devices of the invention providehuge benefit to various medical procedures. For example, it is believedthat in blood-banking applications in France, all thermoplastic tubeconnections made with currently available technology must be inspected,e.g., by pressurizing with air and holding the connected joint underwater to check for leaks. Such inspection is time consuming. Inaddition, a significant amount of connected joints fail and have to beredone or the resulting products must be discarded, thereby adding tothe overall cost and time, and loss of valuable blood materials. Byeliminating or significantly reducing the failure rate, methods anddevices of the invention significantly reduce the time and cost ofconnecting tubes.

The present invention will now be described with regard to theaccompanying drawings which assist in illustrating various features ofthe invention. In this regard, the present invention generally relatesto various devices and methods for connecting thermoplastic tube ends.

FIG. 1 is a schematic, fragmentary longitudinal section view of athermoplastic tube having a sealed end. Two configurations areillustrated in FIGS. 1A and 1B. As can be seen in FIG. 1A, the distalend of the sealed end 180 comprises thermoplastic tube 100, which has anouter diameter 110 and an inner diameter 114. The thermoplastic tube 100is inserted into and is hermetically sealed with a thermoplastic cap150, which comprises the sealed end 180. The thermoplastic cap 150 hasan outer diameter 160 and an inner diameter 164. The inner diameter 164of thermoplastic cap 150 should be sufficiently large enough toaccommodate thermoplastic tube 100 having the outer diameter 110. Theinner diameter 164 of thermoplastic cap 150 should also be sufficientlysmall enough to form a hermetically sealed connection betweenthermoplastic tube 100 and thermoplastic cap 150.

In some embodiments, the inner diameter 164 of thermoplastic cap 150 isslightly smaller than the outer diameter 110 of thermoplastic tube 100but is sufficiently large enough to allow insertion of thermoplastictube 100 into thermoplastic cap 150, for example, by slightly expandingthe inner diameter 164 with heat or by lubricating the outer surface ofthermoplastic tube 100, for example, with a solvent thus forming acohesive joint between thermoplastic components. Such configurationtypically provides hermetically sealed connection between thermoplastictube 100 and thermoplastic cap 150 without the need for any adhesive.Alternatively, when the inner diameter 164 is slightly larger than theouter diameter 110, an adhesive can be used to connect and/orhermetically seal thermoplastic tube 100 with thermoplastic cap 150.When an adhesive is used, such adhesive should be compatible with thedesired application. Suitable adhesives include, but are not limited to,urethane adhesives, and solvent mediated adhesives.

FIG. 1B is a schematic illustration of one-piece longitudinal sectionview of a thermoplastic tube 100B having a sealed end 180B. In thisembodiment, the inner diameter is relatively constant throughout, i.e.,114B and 164B are equal within the manufacturing limitation. However,the wall thickness defined by the difference between the outer diameterand the inner diameter is significantly different between the tubesection distal to the sealed end and the tube section proximal to thesealed end. That is, the wall thickness defined by the differencebetween 160B and 164B is significantly higher than the wall thicknessdefined by the difference between 100B and 114B. Unless stated or thecontext requires otherwise, the term “proximal to the sealed end” referto that portion of the thermoplastic tube having the wall thickness orthe cross-sectional area that is substantially larger than thethermoplastic tube portion that is distal to the sealed end. Thus theterms “proximal” and “distal” are operational terms based on the wallthickness and/or the cross-sectional area of the tube. Unless stated orthe context requires otherwise, the term “cross-sectional area” refersto the transversal cross-sectional area of the thermoplastic tube, i.e.,cross-sectional area that is perpendicular to the longitudinal axis ofthe thermoplastic tube.

Referring again to FIGS. 1A and 1B, regardless of the configuration, insome embodiments, the outer diameter 160 that is proximal to the sealedend 180 is substantially greater than the outer diameter 110 that isdistal to the sealed end 180. In addition, the wall thickness (definedby the difference between the outer diameter 160 and the inner diameter164) proximal to the sealed end 180 is substantially greater than thewall thickness (defined by the difference in the outer diameter 110 andthe inner diameter 114) distal to the sealed end 180.

Typically, thermoplastic tube 100 is flexible. However, it should beappreciated that the scope of the invention does not limit thethermoplastic tube 100 to be flexible. The material of thermoplastictube 100, particularly the portion that is proximal to the sealed end180, should be capable of becoming molten when heated. Conventionalmedical tubing materials, such as, but not limited to, thermoplastics,thermoplastic elastomers and PVC may be used. Furthermore, the tubingcan be co-extruded with a PVC core of higher melt temperature and anouter sleeve with similar melt temperature as compared to the capcomponent 150. The higher melt temperature core can allow a differentmelt flow characteristic to positively influence self-opening feature.In addition, the tubing can be co-extruded with a thermoplasticpolyolefin core and thermoplastic outer sleeve allowing solvent bondingto the thermoplastic cap component 150. The polyolefin core can thenallow a different melt flow characteristic to influence self opening.Moreover, the same property can be achieved using other thermoplasticresins co-extruded in a similar manner. Alternatively, the inverse canalso be used where the co-extruded core can be a lower melt temperaturethermoplastic ensuring a seal is formed in the center of the tubing thatcan be later opened if desired.

In some embodiments of the invention, thermoplastic cap 150 is used.Within such embodiments, in some instances both thermoplastic 100 andthermoplastic cap 150 have the same melting temperature. In otherinstances, thermoplastic cap 150 has a different melting temperaturethan thermoplastic tube 100. Within these instances, in some casesthermoplastic cap 150 has a higher melting temperature thanthermoplastic tube 100. Still in other cases, thermoplastic cap 150 hasa lower melting temperature than thermoplastic tube 100.

FIG. 2 illustrates a schematic, longitudinal section view of variousthermoplastic cap configurations. Regardless of any particularconfiguration, thermoplastic cap 200 comprises an orifice 204 which isadapted for receiving a thermoplastic tube (not shown in FIG. 2) and asealed end 280. The inner diameter of orifice 204 is adapted to receiveand be hermetically sealed with the thermoplastic tube, when thethermoplastic tube is coupled with or connected to thermoplastic cap200. In addition, thermoplastic cap 200 comprises channel 208 that is influid communication with orifice 204. Channel 208 may have the sameinner diameter or a different inner diameter than the inner diameter oforifice 204. Thermoplastic cap 200 can also include a wall 212positioned between orifice 204 and channel 208. Wall 212 is adapted forproviding a stopping point when a thermoplastic tube is inserted throughorifice 204. However, it should be appreciated that a thermoplastic tubeneed not be inserted all the way to wall 212. All that is required is asufficiently tight hermetic seal be formed between a thermoplastic tubeand thermoplastic cap 200. As illustrated in FIG. 2, sealed end 280 canbe of various shapes and configurations.

While the inner diameter of orifice 204 is typically larger than theinner diameter of channel 208, as illustrated in FIGS. 2A-C, in someembodiments, the inner diameter of orifice 204 is smaller than the innerdiameter of channel 208. In this configuration, rather than insertingthe thermoplastic tube to orifice 204, thermoplastic cap 200 is insertedinto a thermoplastic tube. That is, the outer diameter of orifice 204 inFIG. 2D is such that it can be inserted into the thermoplastic tube andform a hermetic seal. Accordingly, the scope of the inventionencompasses thermoplastic caps that receive a thermoplastic tube as wellas thermoplastic caps that are inserted into a thermoplastic tube.

Optionally, thermoplastic cap 200 can also include a flange 216. Flange216 can encompass the entire circumference of thermoplastic cap 200 orit can encompass only a portion of the circumference of thermoplasticcap 200. Flange 216 is useful for various purposes. For example, it canbe used as a stopping point during melting of the sealed end 280 to formmolten thermoplastic. That is, flange 216 can be used to allow formationof molten thermoplastic up to where flange 216 is located. Since thecross-section area of the thermoplastic is greater where flange 216 islocated, joining of molten thermoplastic at flange 216 allows strongerjoint connection as well as ease of joint formation due to its greatersurface area for forming a joint connection. Furthermore, flange 216 canbe used to aid in opening of the lumen after the thermoplastic tubes areconnected. For example, one can use flange 216 to pull apart the lumenof connected thermoplastic tubes or the elasticity modulus associatedwith this flange could restore the lumen to the open condition followingthe joining of the tube ends.

Another aspect of the invention provides a method and devices forjoining thermoplastic tubes in a sterile condition. In this aspect ofthe invention, thermoplastic tube configuration having a greatercross-sectional surface area proximal to the sealed end is provided. Thepresent inventors have found that thermoplastics having a largercross-sectional thermoplastic surface area allow stronger and/or easierconnection between the thermoplastic tubes. Without being bound by anytheory, it is believed that the ease, and/or reliability, of forming anairtight connection between thermoplastic tube ends is proportional tothe cross-sectional thermoplastic surface area, i.e., thermoplastic tubeends having a larger cross-sectional thermoplastic surface area areeasier to form reliable, strong and/or airtight connection. Accordingly,it is believed that the margin of error and/or the failure rate isinversely proportional to the cross-sectional thermoplastic surfacearea. Hence, some aspects of the invention reduce the margin of errorfor connecting thermoplastic tube ends by providing thermoplastic tubeends having a larger cross-sectional thermoplastic surface area relativeto the conventional thermoplastic tubes that are typically used informing a sterile connection. For example, conventional thermoplastictubes that are used in medical procedures have inner diameter of about0.16 inches with the cross-sectional thermoplastic area of about 6.2mm.sup.2 (0.6 mm wall thickness). By increasing the cross-sectionalthermoplastic area to about 16 mm.sup.2 (1.2 mm wall thickness) or toabout 27 mm.sup.2 (1.8 mm wall thickness), or to about 75 mm.sup.2 (3.6mm wall thickness), it has been found that a significantly strongerconnection between thermoplastic tube ends can be formed. In addition,increasing the cross-sectional thermoplastic thickness alsosignificantly reduces the rate of joint failure.

In one embodiment, a thermoplastic cap, such as those shown in FIG. 2optionally having flange 216, is provided. As discussed above, thethermoplastic caps can be used to cap a conventional thermoplastic tubeto provide a sealed end having a larger cross-sectional thermoplasticsurface area. Alternatively, a thermoplastic cap such as thoseillustrated in FIG. 3 can be used to provide a larger cross-sectionalthermoplastic surface area. It should be appreciated that thermoplasticcaps in the accompanying Figures are for illustrative purposes only, andthe scope of the invention includes any thermoplastic cap configurationthat provides increased cross-sectional thermoplastic surface areaand/or increased cross-sectional thermoplastic thickness.

One exemplary method for connecting a first and a second thermoplastictubes together transversely of the axis of each tube is schematicallyillustrated in FIG. 3. In FIG. 3, the first thermoplastic tube 300 andthe second thermoplastic tube 350 having thermoplastic caps 304 and 354are shown. In this illustration, thermoplastic tubes 300 and 350 areinserted into and hermetically sealed with thermoplastic caps 304 and354 to provide sealed ends 308 and 358, respectively. In this particularillustration, the thickness of thermoplastic caps 304 and 354 issubstantially greater than the thickness of thermoplastic tubes 300 and350. The cross-sectional thermoplastic surface area proximal to thesealed ends 308 and 358 is substantially greater than thecross-sectional surface area distal to the sealed end. In addition, thethermoplastic wall thickness is substantially greater proximal to thesealed end relative to the wall thickness distal to the sealed end.

For connecting first thermoplastic tube 300 with second thermoplastictube 350, the sealed ends 308 and 358 are optionally, and preferably,compressed as shown in FIG. 3B. This compression closes the lumens (ortube interiors) 312 and 362 proximal to the sealed ends 308 and 358,respectively. Such closure prevents the lumen of tubes 300 and 350 fromfilling with molten thermoplastic while being pressed into the hot plateas described below. In addition, such closure also prevents the lumensfrom being exposed to the atmosphere and maintains the thermoplastictubes in an aseptic condition. Additionally, such closure allows removalof interior contents from the molten thermoplastic preventing externalleaks due to expanding tubing contents with rising temperature.

The sealed ends 308 and 358 are then heated, either by a direct contactwith a heated plate 380 or by other heating means known to one skilledin the art (not shown), including non-direct contact means such as thosediscussed above. As shown in FIG. 3C, thermoplastic tubes are pressedinto hot plate 380 in a direction shown by arrows A and B. This pressingof the thermoplastic tubes into hot plate 380 melts the thermoplastic atthe sealed end to produce molten thermoplastic. It should be appreciatedthat the sealed ends 308 and 358 can optionally be cut using a cuttingblade, which may be the same as hot plate 380, prior to producing moltenthermoplastic. Preferably the cutting blade is heated to allowsimultaneous cutting and melting of the thermoplastic. As used herein,the term “molten thermoplastic” refers to both melted thermoplastic aswell as softened thermoplastic resin that is capable of adhering toother molten thermoplastic.

FIG. 3C shows molten thermoplastic 316 and 366 flowing away from thecompressed lumens of thermoplastic tubes and caps. It should beappreciated that the likely contaminated surface portions 308 and 358 ofcaps 304 and 354 are the first portions of the cap to become molten. Asthe surface regions melt and flow away from the lumen, any contaminantscontained thereon are effectively flushed or removed away from the lumenthus maintaining lumen sterility. In some embodiments of the invention,it is advantageous to produce excess molten thermoplastic 316 and 366 asshown in FIG. 3D. Excess molten thermoplastic flow further helps carryaway from the lumen any contaminants that might have been on the surfaceof the tube or the cap. After producing molten thermoplastic, hot plate380 is removed as shown in FIG. 3E, while maintaining airtight closureof interior of thermoplastic tubes 300 and 350. The molten ends are thencontacted with one another as shown in FIG. 3F to form a joint betweenthermoplastic tubes 300 and 350. The thermoplastic tubes may optionallybe further advanced in the direction of arrows A and B (see FIG. 3C),thus producing additional molten thermoplastic flow and purging themolten surfaces of any air born contaminant that may have landed on themolten surface following removal of hot plate 380. When excess moltenthermoplastic 316 and 366 is present, the resulting joint betweenthermoplastic tubes 300 and 350 may include flange 330. When excessmolten thermoplastic is present, it provides a greater surface area forforming a connecting joint. As discussed above, the greater surface areareduces the rate of joint failure as well as providing a stronger and/oreasier joint formation.

After joining the molten thermoplastic ends together, the external force(e.g., clamp) is removed allowing the lumen to regain its originalshape. See, for example, FIG. 3G. In some embodiments, the thermoplasticwall proximal to the sealed end has a sufficient elasticity modulus toopen the interconnecting lumen without a need for any external force.Generally the required elasticity modulus is a result of thethermoplastic tube's wall thickness and relatively low meltingtemperature as compared to the sealed end. In other embodiments, flange330 can be used to aid in opening the lumen, e.g., by pulling flange 330away from the lumen or by virtue of the elasticity modulus of the flangeand/or the thermoplastic tubes themselves. In other embodiments, elasticmodulus of flange 216 maybe used to open the lumen without any externalforce.

FIG. 3H is a transversal cross-sectional view of thermoplastic tube 300shown in FIG. 3D. During its contact with hot plate 380 (not shown inFIG. 3H, but see FIG. 3D), molten thermoplastic is produced proximal tothe sealed end 308. As thermoplastic tube 300 is pressed into hot plate380, molten thermoplastic flows away from the interior of thermoplastictube 300. Such molten thermoplastic flow maintains aseptic condition ofthe interior of thermoplastic tube 300. Generally, when excess moltenthermoplastic flow is used, the surface area of the molten thermoplasticis at least about 100% greater, preferably at least about 250% greater,and more preferably at least about 500% greater, than thecross-sectional area of the sealed end. In one particular example, whenexcess molten thermoplastic flow is used, the surface area of the moltenthermoplastic is from about at least 200% to about 800% greater than thecross-sectional area of the sealed end.

Suitable thermoplastic tube connecting apparatuses are well known to oneskilled in the art and include, but are not limited to, those discussedin the Background of the Invention section as well as U.S. Pat. Nos.6,341,637; 6,026,882; 6,679,529; 6,913,056; 4,443,215; 4,412,835;4,507,119; 5,345,070; and PCT Publication Nos. WO 82/02528; and WO02/087491, all of which are incorporated herein by reference in theirentirety.

In conventional thermoplastic tube connecting apparatuses that use athermoplastic melting plate, the surface area of the thermoplasticmelting plate that is heated during operation is significantly largerthan the area needed to produce molten thermoplastic from thethermoplastic tube. This results in a significantly higher energyrequirement than necessary since the excess heat dissipates from theheated surface area of the thermoplastic melting plate without beingused.

Accordingly, another aspect of the present invention provides athermoplastic melting plate that is designed to significantly reduce oreliminate unnecessary heat consumption during its operation. In someembodiments, a thermoplastic melting plate that is adapted to be usedwith a heat weld thermoplastic tube connecting apparatus is provided.FIGS. 4A-4C illustrate some embodiments of the thermoplastic meltingplate of the invention. As can be seen, the thermoplastic melting plate400 comprises a heat transferring material 404 that is adapted formelting a thermoplastic tube to produce molten thermoplastic. As usedherein, the term “heat transferring material” refers to any material ofa component of an apparatus that is used to produce molten thermoplasticfrom the thermoplastic. In addition, thermoplastic melting plate 400comprises a front surface 408A; a back surface 408B; an insulatingmaterial 412 substantially covering front surface 408A and back surface408B; an exposed heat transferring material portion (416A and 416B inFIGS. 4A and 416 in FIGS. 4B and 4C) within the insulating material 412such that the exposed heat transferring material portions are adaptedfor melting the thermoplastic tube 450 and the thermoplastic cap 454 toproduce molten thermoplastic; and an interface portion 420 foroperatively connecting thermoplastic melting plate 400 to a heat weldthermoplastic tube connecting apparatus (not shown). Typically,interface portion 420 is adapted to be operatively connected to aheating element of the heat weld thermoplastic tube connecting apparatus(not shown).

The thermoplastic melting plate can be made of any material that canconduct heat. Exemplary materials that are suitable for thermoplasticmelting plates include metals, heat transferring ceramics, metal alloys,as well as other materials that are known heat conductors, such as aflash heater available from Watlow Electric Manufacturing Company (St.Louis, Mo.). In one specific embodiment, the thermoplastic melting plateis adapted for use with tube connecting apparatuses such as the TerumoSterile Tubing Welder, Model SC-201A (available from Terumo MedicalCorp. Somerset, N.J., U.S.A.). In one embodiment, the thermoplasticmelting plate is a thin plate that can optionally be used to both heatand cut thermoplastic tubes.

In other embodiments, the thermoplastic melting plate can be a thinplate that is sized to correspond to the area to be sealed. Such a platedoes not need to have any insulating material and can heat and cool veryrapidly due to its thinness.

In other embodiments, thermoplastic melting plates of the invention areadapted to be useful in any thermoplastic connecting apparatus that isschematically illustrate in FIG. 3 as well as those that do not requirea direct contact to produce molten thermoplastic. As will be recognized,in embodiments where the thermoplastic tube is not directly contacted tothe thermoplastic melting plate, the thermoplastic melting plate isheated to a temperature sufficient to melt the thermoplastic tube whenit is placed near the thermoplastic melting plate.

The insulating material, when used, substantially covers the portion ofthe thermoplastic melting plate that is not used in thermoplastic tubeconnection operation. In one embodiment, the insulating materialcomprises aluminum silicate, a heat insulating ceramic, or a combinationthereof.

In some embodiments, the thermoplastic melting plate can also be used tocut the thermoplastic tube. In such embodiments, the thermoplasticmelting plate comprises an edge 424 (see FIG. 4B) that is sufficientlyshaped when heated to cut a thermoplastic tube.

Another aspect of the invention provides a thermoplastic tube connectingapparatus comprising the thermoplastic melting plate disclosed herein.

One of the problems associated with a hot plate thermoplastic tubeconnection apparatus is the potential for degraded plastic and/or moltenplastic to build up on the hot plate. In some cases, such problem iseliminated by using a disposable hot plate. However, this solution addsto the overall cost and time for connecting thermoplastic tubes byrequiring the hot plate to be replaced after each operation.

Accordingly, another aspect of the present invention provides a deviceand a method for eliminating degraded plastic and/or molten plastic frombuilding up on the hot plate without a need for using a disposable hotplate. As illustrated in FIGS. 5A and 5B, one embodiment of such athermoplastic tube connecting apparatus comprises a thermoplasticmelting plate 500 that is adapted for melting a thermoplastic tube (504Aand 504B) thereby producing a molten thermoplastic tube end; and a thinfilm 508 that is adapted for being placed between the thermoplastictubes 504A and 504B, and the thermoplastic melting plate 500 such thatthe thermoplastic tubes do not come in direct contact with thermoplasticmelting plate 500 during its operation.

Thin film 508 can be comprised of any material that readily conductsheat and is sufficiently strong enough to withstand tear duringoperation. When thin film 508 is used, thermoplastic melting plate 500should not have any sharp edges as any sharp edge may tear thin film508. Accordingly, in some embodiments, thermoplastic melting plate 500has a rounded dull edge which reduces the risk of causing any tear ofthin film 508. Exemplary materials that are suitable for thin film 500include, but are not limited to, thin malleable metallic sheets (such asaluminum foil and copper foil), polytetrafluoroethylene, polyester, QFoil (available from EGC Enterprises Inc., Chardon, Ohio), and acombination thereof.

The thermoplastic tube connecting apparatus can also include a roller, adrum, a cartridge, or other mechanical means known to one skilled in theart that allows a different portion of thin film 508 to come in contactwith thermoplastic tubes during subsequent thermoplastic tube connectingoperations. Such mechanism is schematically represented as item 512 inFIGS. 5A and 5B. The amount of thin film 508 advancement during eachthermoplastic tube connection operation can be controlled by a computer(not shown) or it can be controlled by a mechanical means such as asprocket or a gear mechanism that is spaced according to the amount ofthin film 508 advancement desired. Alternatively, friction based rollerscan be used to advance the desired amount of thin film 508. Anothermethod is to provide a plurality of sprocket drive holes (not shown)near the edge of thin film 508. Such sprocket drive holes can beprecision punched to maintain a uniform spacing and to allow properadvancement of thin film 508 with each thermoplastic tube connectionoperation using, for example, tractor drive mechanism (not shown).

Regardless of the mechanism used, each thermoplastic tube connectionoperation allows a fresh new surface area of thin film 508 to come incontact with thermoplastic tubes, thereby preventing any direct contactbetween thermoplastic melting plate 500 and thermoplastic tubes 504A and504B. Such operation prevents any build up of degraded plastic and/ormolten plastic on hot plate 500 and provides a clean surface forthermoplastic melting without the need for using a disposablethermoplastic meting plate.

The thermoplastic tube connecting apparatus can also include one or moreguides 516 that are adapted to allow thermoplastic hot plate 500 to beproperly positioned and allow thin film 508 to be operatively connectedto thermoplastic hot plate 500. Guide 516 can be a separate roller,drum, or other mechanical device known to one skilled in the art.Alternatively, guide 516 can be part of a thermoplastic tube holder asdiscussed in detail below.

As shown in FIG. 5C, thermoplastic tube connecting apparatus of theinvention can comprise a thermoplastic tube holder 520 that can hold aplurality of thermoplastic tubes (or a plurality of thermoplastic tubeholders). This configuration allows simultaneous connection of aplurality of thermoplastic tubes. This is particularly useful with thethermoplastic tube connecting apparatus that comprises a thin film 508which eliminates a need for disposable thermoplastic melting plateand/or the direct contact between thermoplastic melting plate 500 andthermoplastic tubes 504A and 504B. In FIG. 5C, thermoplastic tube holder520 can also serve as a guide that allows thermoplastic hot plate 500 tobe properly positioned.

Although FIG. 5C shows a single thermoplastic melting plate 500 withthin film 508, it is understood that multiple tube connections can bemade with a plurality of thin thermoplastic melting plates, wherein eachplate is associated with a pair of the multiple tube connections.

Achieving simultaneous multiple thermoplastic tube connection isadvantageous in various medical procedures compared to the conventionalsterile thermoplastic tube connection methods that use a single costlydisposable blade for each connection. As shown in FIGS. 6 and 7, use ofthin film 608 and 708, respectively, eliminates the need for replacingthe hot plate 600 and 700, respectively, after each tube connectionoperation. In part, thin film 608 and 708 prevents molten tubing plasticfrom adhering to hot plate 600 and 700, respectively. FIGS. 6 and 7illustrate simultaneous multiple tube connection that can be used invarious medical procedures, for example, for removing platelets frombuffy coats previously separated from whole blood. One example ofcurrently available apparatus for removing platelets is the OrbisacSystem available from Gambro BCT, Inc. (Lakewood, Colo., USA). Buffycoat, produced from a whole blood donation, is a combination ofplatelets and white blood cells, as well as small amounts of red bloodcells and plasma.

As a brief background, in the mid-1970's, European blood centers beganto remove the buffy coat from separated red blood cells. It wasdiscovered that the buffy coat contained a high concentration ofplatelets, a blood component vital to blood clotting.

The majority of platelets collected during a whole blood donation arefound in the buffy coat layer, which settles between red blood cells andplasma during centrifugation. To extract as many of these platelet aspossible, buffy coats are pooled from many donations and re-spun in acentrifuge to separate the platelets from the rest of the buffy coat.The platelets collected contain some white blood cells even aftercentrifugation, so the platelets are filtered to remove white bloodcells before storage and transfusion. This process is calledleukoreduction.

Platelets help the blood to clot. People with certain diseases likethrombocytopenia, leukemia, and other cancers have a reduced number ofplatelets in their bloodstreams. Without adequate platelets, they bleedabnormally and bruise easily. Regular platelet transfusions areessential treatment for these and other patients. Typically, the processto create pooled, leukoreduced platelets from whole blood istime-consuming, labor-intensive and requires many manual steps.

Processing whole blood buffy coat platelets requires multi-step,post-donation processes: pooling, centrifugation, expression, andfiltration. These manual processes are labor-intensive and timeconsuming. As expected, anytime a task is performed manually, there isan increased risk of processing errors. Whole blood donations areseparated into components via gravitational force in a centrifuge. Theforce of the centrifuge causes the whole blood to separate into layersbased on cell density. The upper layer captured in the centrifuge isplasma. The middle layer is the buffy coat. The bottom, heaviest layeris packed red blood cells. There are various automated apparatuses toperform the buffy coat processing steps, such as the Orbisac System.Typically, these apparatuses perform various tasks, such as pooling,centrifugation, expression, and filtration.

Some embodiments of the thermoplastic tube connecting apparatus of theinvention allow simultaneous multiple thermoplastic tube connection,such as those useful in collecting platelets and processing buffy coatspooled from many blood donations. As shown in FIG. 6, five (5) differentbags (604A to 604E) each containing buffy coat are simultaneouslyconnected to a centrifuge bag 650 used in combination with the OrbisacSystem, using hot plate 600 and a thin film 608 as described herein. Inaddition, a bag containing platelet storage solution or plasma 612 isalso simultaneously connected to the centrifuge device 650.Thermoplastic tubes from bags 604A-604E and 612 are placed such thatthey are properly positioned for connection, see for example FIG. 5C. Itshould be appreciated that some devices may require the bags beconnected in series such as that depicted in FIG. 7. A tube holder (520in FIGS. 5C and 800 in FIG. 8), which optionally, and preferably, clampsand closes the lumen, holds the thermoplastic tubes (504 in FIGS. 5C and804 in FIG. 8) in proper position. The tube holder (520 in FIGS. 5C and800 in FIG. 8) also moves tubing ends against an optionally thin film508 covered hot plate 500 to produce molten thermoplastic tube ends.After removing the hot plate 500, the tube holder 520 moves the moltenthermoplastic tube ends together to form joint connections. A tubingmanifold 624 connects the plurality of thermoplastic tubes 628A-628F tothe centrifuge bag (or other container) 650.

After connecting buffy coat bags 604A-604E to tubing manifold 624, buffycoats, along with the storage solution, are pooled in the centrifuge bag650 and the platelets are separated from the rest of the buffy coat. Thecollected platelets are then transferred to platelet storage bag 612 andthen optionally filtered to further remove white blood cells.

Alternatively, as shown in FIG. 7, a platelet storage solution bag 712and a plurality of buffy coat bags (e.g., 716A-716E) are connected asshown using the thermoplastic tube connecting apparatus of theinvention. Formation of such plurality tubing connections are describedherein. In FIG. 7, buffy coats are pooled in to a centrifuge bag 720.The contents of bag 720 is then centrifuged, e.g., in a conventionalbucket centrifuge, to separate the platelets (centrifuge step notshown). The collected platelets are again optionally filtered to furtherremove white blood cells and are then transferred to a storage bag 724.Unlike the process illustrated in FIG. 6, process of FIG. 7 does notrequire a tubing manifold 624.

Additional objects, advantages, and novel features of this inventionwill become apparent to those skilled in the art upon examination of thefollowing examples thereof, which are not intended to be limiting.

The foregoing discussion of the invention has been presented forpurposes of illustration and description. The foregoing is not intendedto limit the invention to the form or forms disclosed herein.

Although the description of the invention has included description ofone or more embodiments and certain variations and modifications, othervariations and modifications are within the scope of the invention,e.g., as may be within the skill and knowledge of those in the art,after understanding the present disclosure. It is intended to obtainrights which include alternative embodiments to the extent permitted,including alternate, interchangeable and/or equivalent structures,functions, ranges or steps to those claimed, whether or not suchalternate, interchangeable and/or equivalent structures, functions,ranges or steps are disclosed herein, and without intending to publiclydedicate any patentable subject matter.

1. A thin thermoplastic melting plate adapted to be used with a heatweld thermoplastic tube connecting apparatus, said thermoplastic meltingplate comprising a heat transferring material that is adapted formelting a thermoplastic tube to produce molten thermoplastic, whereinsaid thermoplastic melting plate comprises: a front surface; a backsurface; an insulating material substantially covering said front andback surfaces; an exposed heat transferring material portion within saidfront and said back surfaces of said insulating material such that saidexposed portion is adapted for melting the thermoplastic tube to producemolten thermoplastic; and an interface portion for operativelyconnecting said thermoplastic melting plate to the heat weldthermoplastic tube connecting apparatus.
 2. The thermoplastic meltingplate of claim 1, wherein said insulating material comprises aluminumsilicate, a heat insulating ceramic, or a combination thereof.
 3. Thethermoplastic melting plate of claim 1, wherein said exposed heattransferring material portion is adapted for contacting thethermoplastic tube to produce molten thermoplastic.
 4. The thermoplasticmelting plate of claim 1, wherein said exposed heat transferringmaterial portion is adapted to produce molten thermoplastic from thethermoplastic tube without contacting the thermoplastic tube.
 5. Thethermoplastic melting plate of claim 1, wherein said interface portionis adapted to be operatively connected to a heating element of the heatweld thermoplastic tube connecting apparatus.
 6. The thermoplasticmelting plate of claim 1 wherein said exposed heat transferring materialportion within said front and said back surfaces are adapted for meltingthermoplastic tube to produce a molten thermoplastic tube end.
 7. Thethermoplastic melting plate of claim 6, wherein said exposed heattransferring material portion is adapted for contacting thethermoplastic tube to produce molten thermoplastic.
 8. The thermoplasticmelting plate of claim 7, wherein said exposed heat transferringmaterial portion is adapted to produce molten thermoplastic from thethermoplastic tube without contacting the thermoplastic tube.
 9. Thethermoplastic melting plate of claim 6 wherein said thin heattransferring material is adapted for melting a plurality ofthermoplastic tubes to simultaneously generate a plurality of moltenthermoplastic tube ends.